Subject: [PATCHv1 2/3] arm: mvebu: add .dts file for Synology DS213j

From: [email-masked] (Arnaud Ebalard)
Date: Mon, 17 Nov 2014 09:25:15 +0100

Hi,

Ben Peddell <[email-masked]> writes:

> On 16/11/2014 11:14 PM, Arnaud Ebalard wrote:
>>>> +	gpio-fan-100-32-35 {
>>> There is some logic to this naming, but i don't remember what it is.
>>> Did you check this is appropriate?
>> The 32-35 is for the MPP i.e. fan uses mpp32 to mpp35 (3 MPP for speed,
>> one for alarm). I don't know what the 100 part means. What I did is I
>> googled to see which fan supported kirkwood models have and noticed
>> that the DS212j uses the exact same fan, i.e. Y.S.Tech FD129225LL-N so
>> I opted for the same naming.
>>
>> On that aspect, you may be able to explain why the speed-map for this
>> fan goes up to 5000 RPM. This fan is supposed to operate at 1900RPM.
>> Note that it does not matter in practice.
>
> On the Kirkwood Diskstations, the first number (100, 120 or 150) refers
> to the middle of the three fan speed resistors,

Would not have found that alone ;-) Thanks for clarifying.

> the second number (15 or
> 32) refers to the first fan control pin, and the third number (18 or 35)
> refers to the first fan alarm pin.
>
> i.e. the 100-32-35 uses fan speed resistors of 33, 100 and 150 ohms,
> uses pins 32-34 for fan control, and uses pin 35 for the fan alarm.
>
> The 5000RPM was interpolated from my measured RPM pulse rate (4200PPM)
> of the 80mm fan in my DS211j (which uses the 150-32-35 fan config) at
> maximum RPM.

Then, I think I need to change the speed map to have 1900 RPM as max
speed. Out of curiosity, how did you measured the RPM pulse rate
exactly?

Cheers,

a+